It is much easier to start hating 

than it is to stop.

Consider how often friendship and love, or even an acquaintance, have changed into hatred. And how rare it is for hatred to transform back.

Hatred is like the proverbial slippery slope that is easy to slide down, incredibly difficult to climb back up. As we begin to hate, we find reasons to justify our feelings and become convinced we are right to feel as we do.

The other person has done something terrible. We have done nothing.

They are guilty of wrongdoing. We are innocent.

With time, we become attached to our hatred for the person, or the people. To stop our hating, we will need to 1) let go of our attachment to it and 2) either admit that our hatred was unwarranted or that it was warranted, but we were wrong to give in to it.

Since as ordinary beings, we do not like giving up attachments or admitting we were in the wrong, it would indeed be easier to not further develop this terrible habit than to attempt to break it.